1. Field of the Invention
The present invention relates to an image display apparatus, in particular, to a configuration of a metal back arranged on a face plate.
2. Description of the Related Art
Field Emission Display (FED) and Surface-conduction Electron-emitter Display (SED) are known as flat display apparatuses based on a light emission principle similar to the cathode ray tube. In such flat display apparatuses, electron beam having high energy is irradiated to phosphors and the phosphors emit light, whereby a desired image is obtained.
A general phosphor screen configuration used in such flat display apparatus is shown in FIG. 6. A light shielding layer 21 and a bank layer 22 are arranged on a face plate 120. A light-emitting body 24 that emits one of the three colors of red, green, or blue is formed in an opening 23 of the light shielding layer 21. The light-emitting bodies 24 are covered by a metal back 125. As shown in FIG. 7, when irradiating the electron beam to each light-emitting body 24R, 24G, 24B of red, green, and blue, the electron beam 27 is irradiated to a central region of each light-emitting body 24R, 24G, 24B and the irradiation amount to the peripheral region is small.
The light shielding layer 21 is made of black substance that lowers reflectance by absorbing outside light, thereby preventing reflection of outside light and enhancing blackness of the screen. The bank layer 22 is a wall that divides each light-emitting body 24 so that the light-emitting body 24 is accommodated at a predetermined position, and normally has a film thickness of about the same extent as the light-emitting body 24. The bank layer 22 is not an essential configuration, and is not used in some configurations.
Normally, the opening 23 is orderly arrayed in dot form vertically and horizontally, and forms a filling section of each light-emitting body 24. The light-emitting body 24 is made of phosphor particles 31 filled so as to cover the opening 23, and performs the desired light emission through irradiation of electron beam. The metal back 125 reflects the light emitted towards the rear plate side from the phosphor particles 31 towards the front side of the display apparatus, thereby enhancing the light emission intensity.
FIG. 8 shows a cross section of a conventional face plate.